Odd Distorted Audio Issue in Ubuntu Studio 23.04

[G M Slater]

I am running Ubuntu Studio v23.04 and am using a Focus Scarlett 2i2 unit as the sound card. Every time I reboot the computer the audio is extremely distorted. To get it back to normal I have to unplug the USB cable from the Scarlett, then plug it back in. I have swapped out USB cables, and the Scarlett is only a couple of months old. Does anyone know what would cause this weird behavior?

[j_e_f_f_g]

Given the number of people recently reporting "distorted audio" specifically with Ubuntu Studio, I'm now wondering if Canonical did something with their audio stack. Try a live distro not based on ubunto to see if the problem disappears.

[Robin Cherry]

I have the same issue in Manjaro with the stock kernel. It's been ongoing for a year through multiple updates and showed the same behaviour in an avlinux live trial. I've never found a fix other than unplugging the interface. Mine does the same thing after turning off jack as well.

[j_e_f_f_g]

Does it happen with all apps, or just apps that use pulseaudio?

In the apps that are affected, can you set them to use alsa directly? And if so, does the problem disappear when you do?

[Robin Cherry]

Does it happen with all apps, or just apps that use pulseaudio?

In the apps that are affected, can you set them to use alsa directly? And if so, does the problem disappear when you do?

On my system it is present at bootup until I unplug the USB from the audio interface and plug it back in, and present after stopping jack until I do the same. My interface is a behringer 404hd. What would be an example of an audio app that doesn't use pulseaudio that wouldn't involve starting jack to troubleshoot?

I suspected that the person from the "digital noise in ubuntu" thread is suffering from the same issue but it isn't possible for them to unplug their interface so who knows.

[j_e_f_f_g]

an example of an audio app that doesn't use pulseaudio that wouldn't involve starting jack to troubleshoot?

ocenaudio allows you to select pulseaudio, jack, or alsa from its settings for audio system. So you can check all 3 with that app to see if the problem is with pulse or jack, or whether it's with alsa itself.

If it's alsa, the only way to fix that is to report it as a bug to the alsa dev list.

[Robin Cherry]

an example of an audio app that doesn't use pulseaudio that wouldn't involve starting jack to troubleshoot?

ocenaudio allows you to select pulseaudio, jack, or alsa from its settings for audio system. So you can check all 3 with that app to see if the problem is with pulse or jack, or whether it's with alsa itself.

If it's alsa, the only way to fix that is to report it as a bug to the alsa dev list.

Cool. I'm going to try this.

[nikgnomicradio]

I'm now wondering if Canonical did something with their audio stack

Ubuntu Studio seems to have done something that is not beneficial for pro-audio users

we have switched to utilized PipeWire by default with the JACK and PulseAudio plugins. This means that, without configuration, all JACK and PulseAudio applications will simply work without much configuration.

While PipeWire is convenient and recommended for most users, we do not recommend it for professional or prosumer audio work at this time

"without configuration" or "without much configuration" ?

A user reported distortion issues with a Focusrite Scarlett to PipeWire 3 months ago - Distorted audio from USB audio device
that was blamed on either a kernel bug or USB device misbehaving
so user reported issue setting the probe-rate in PipeWire to ALSA developers - bug 216976 - Scarlett Solo 3rd gen plays/records distorted audio

I would suggest UbuntuStudio users with audio distortion issues try using a Live ISO of AVLinux to check if audio is distorted in PulseAudio or JACK

[Robin Cherry]

I went to troubleshoot my own situation and realised that the boot up issue has resolved itself but the issue when stopping and closing jack has not. Periodic updates must have fixed it. For anyone who wants to compare software versions my system is running the following. Linux 6.2.12, pulseaudio 16.1, alsa 1.2.8, jack2 1.9.22.